I've heard people say that there is a series of comics where Batman is actually Thomas Wayne instead of his son, Bruce.
Where can I find this? What is the series called?
The Batman encountered in the Flashpoint universe, the lead-up to the New 52 reboot is actually Thomas Wayne, Bruce having been killed on that fateful night instead of Thomas, which explains his motivation for fixing whatever created the Flashpoint universe.
In Flashpoint. Spoilers (but you already know that)!
Basically, Flash changed the timeline to save his mama. So instead of Thomas and Martha Wayne getting shot, Bruce got shot. So Thomas, out of veagneance, became Batman. The difference is that Thomas is not afraid to kill, and is darker. Extra: the Joker here is Martha.
If you are interested in seeing this Thomas Wayne on screen in action as Batman, I suggest you check out the animated film called Justice League: The Flashpoint Paradox.
Flashpoint is the comic event that birthed the New 52-niverse (or killed the original DC universe, if you're being negative about it). Here's the official synopsis, if you're not worried about spoilers:
When time travel allows a past wrong to be righted for Flash and his family, the event’s temporal ripples prove disastrous, creating a fractured, alternate reality where the Justice League never formed, and even Superman is nowhere to be found. Amidst a new world being ravaged by a fierce war between Wonder Woman’s Amazons and Aquaman’s Atlanteans, Flash must team with a grittier, more violent Batman and government agent Cyborg to restore the continuity of Flash’s original timeline.
I love that Thomas Wayne is Batman, mostly because I love the idea that all members of the Wayne family are genetically predisposed to fighting crime while dressing like bats. Anyways, Flashpoint does have a pretty epic voice cast:
Primetime television stars Justin Chambers (Grey’s Anatomy) and Kevin McKidd (Grey’s Anatomy), the voices of Barry Allen/Flash and Thomas Wayne/Batman, respectively, unite with numerous greats of television and film to fashion the famed animated roles. Adding to the celebrity-laden voice cast and providing thrilling additions to the Justice League series are Michael B. Jordan (Fruitvale, Friday Night Lights, Chronicle) as Cyborg, C. Thomas Howell (Southland, The Outsiders) as Thawne/Professor Zoom, Nathan Fillion (Castle) as Hal Jordan/Green Lantern, Ron Perlman (Hellboy) as Slade and Deathstroke, Dana Delany (Body of Proof) as Lois Lane, Cary Elwes (The Princess Bride) as Aquaman, Danny Huston (Magic City) as General Lane, Sam Daly (The Office, The Daly Show) as Superman, and Kevin Conroy (Batman: The Animated Series) as Batman.
Way back in Detective Comics #235 (September, 1956) in a story entitled The First Batman Thomas Wayne wears a bat-like costume to a costume-party (complete with mask but with large wings instead of a cape and no Bat-emblem on the chest). Whilst wearing this he fights off some thugs who abduct him. Years later as an adult Bruce discovers old home film-footage of the incident and realises this may actually have led to his father's later murder. He also reasons that a subconscious memory of the incident may have played a part in his decision to adopt a bat as his symbol and crime-fighting persona. I read this story as a child - I wish I still had it.
To see Thomas Wayne in all his glory as The Batman, there are two essentials you should get. I've provided Amazon links to both here for your convenience. The first is the trade paperback version of Flashpoint, the event leading up to DC's New 52 universe launch. The second is the animated film version of the event.
Here's the spoiler(ish) summary of what happens in both:
Barry Allen (aka The Flash) uses the Speed Force to go back in time and prevent his mother from being murdered. This single change causes ripples throughout time, such that when Barry returns to the present, he never became The Flash and there is no Justice League. The world is being ravaged by a war between Atlantis & Themyscira, and it appears that humanity may be destroyed regardless of the victor. Barry sets out to gather his former colleagues, beginning with Batman (now Thomas Wayne instead of Bruce), in an attempt to fix the timeline before the world is destroyed. And even if Barry DOES manage to fix his mistake, things may never be the same again.
Suffice to say, there's much more to the story - including who's ultimately behind it all, how the war really started, etc., but I don't want to give it ALL away here.
It seems everyone knows Thomas Wayne was Batman in Flashpoint, but he was also Batman in the New 52 series Earth 2.
In this universe the attack on the Waynes was a mob hit. Thomas survived but faked his death went into hiding. Bruce, not knowing his father was alive, became the Batman, but he died when the forces of Darkseid invaded. Thomas Wayne then took up the mantle of the Batman to honor his son and atone for his own misdeeds.
Flashpoint is not the only arc where this happens. It happens somewhere in the eighties, maybe in a one off alternate timeline story.
Looks like Thomas Wayne wore a bat costume to a party in the main timeline, and it's referenced a few times over the course of the comics.